“CubeSats are not toys.” Scientific production of small satellites could bring a big hit | science

In orbit a few hundred kilometers above the planet are two satellites, each about the size of half a loaf of bread, that measure the bursts of light-speed electrons that sometimes fall into the atmosphere. When the researchers first launched them in 2015, they had hoped the small satellites would last 3 months before failing. More than 7 years later, they’re still transmitting information about the change and location of the electron bursts — and the team has 19 published papers to show for the $1.2 million mission, called FIREBIRD II.

The success of FIREBIRD II and missions like it are changing the way scientists think about the study of space weather, the field of space physics that deals with the activity of charged solar particles and their impact on Earth. Space weather missions using small satellites known as CubeSats got more bang for their buck than NASA’s larger missions, producing more than four times the number of publications per dollar, according to a the last study. “CubeSats are not toys,” says Amir Caspi, a solar astrophysicist at Southwest Research Institute and an author of the study. “CubeSats are real science tools that can achieve real science.”

Like prefabricated houses, CubeSats are similarly constructed from the outside using modular building blocks. Costs are low because many of the components are standardized and because lightweight satellites can be loaded into rockets as “rideshares” alongside larger missions. With low costs, researchers can take more risks, using inexpensive, consumer-grade electronics rather than specialized space-qualified parts. With low barriers to entry, CubeSats have democratized space science, but until recently many scientists thought they were little more than trinkets for students to play with.

University of New Hampshire solar physicist Harlan Spence and his colleagues wanted to quantify the scientific value of CubeSats. They examined the science results of FIREBIRD II and four other CubeSat space weather missions that cost between $1.2 and $1.3 million each and weighed an average of 3 kilograms. They compared CubeSat production with that of five of NASA’s largest missions that cost between $72 million and $1.5 billion and weighed hundreds or thousands of kilograms.

Surprisingly, the large missions produced far more science—nearly 86 publications per year since inception—compared to roughly two publications per year for CubeSats. But when science output was weighed against mission cost, CubeSats came out on top, producing 1.6 publications per year since launch per million dollars spent, versus 0.4 for large missions, the researchers report in a preprint posted June 7 in arXiv. and now accepted for publication in Space weather diary. FIREBIRD II, for example, produced 2.2 issues per year per million dollars spent. NASA’s $600 million Van Allen Probes (VAP) mission, which also studied space weather, produced 0.1 publications per million dollars per year.

The researchers also attempted to quantify the caliber of published research by looking at the impact factors of the journals in which the papers were published compared to the number of papers published per journal. The five CubeSat missions had an average calculated impact factor of 3.8, while the five largest missions averaged 4. For Spence, this shows that “the most successful CubeSat missions are able to hold their own with the big missions.”

In the paper, the authors argue that CubeSats have a vital and cost-effective role to play in predicting space weather, which can cause power outages, interfere with GPS systems and expose on-board aircraft to levels of harmful radiation. Cross-referencing data from many CubeSats in small fleets helps researchers determine the patterns of movement of electronic activity occurring in the radiation belts, just as weather stations do to predict patterns on Earth, says Eftyhia Zesta, an astrophysicist at the Center of NASA Goddard Space Flight which works with both CubeSats and larger missions. “Until there were automated weather stations in every corner of the planet that fed data into large simulation models, we didn’t have good weather forecasts,” she says. “CubeSats can be a very powerful tool for that.” FIREBIRD II, for example, used two CubeSats together to fill information gaps that VAP’s single satellite was unable to address on its own.

But Jonathan McDowell, an astrophysicist at the Harvard-Smithsonian Center for Astrophysics who works with CubeSats and multibillion-dollar missions like the Chandra X-ray Observatory, says CubeSats have their scientific limits. “There are niches where CubeSats are not only valuable, but absolutely the way to go.” McDowell says. “But I think there are whole classes of probes where you really need the big flags, and CubeSats just aren’t going to cut it.”

And Zesta points out some ways in which the study may have compared apples and oranges. For starters, she says, the study highlighted university-built CubeSats funded by the National Science Foundation, and likely didn’t include the full engineering salaries of the graduate students who worked on the project as part of the mission’s total cost. NASA CubeSats, like the ones Zesta works on, are not subsidized in the same way and typically cost between $4 million and $8 million. For Zesta, excluding graduate student work not only creates an uneven comparison, but also gives the inaccurate impression that CubeSats can be built for just a few million dollars. Caspi admits that calculating the true cost and true outcome of each mission is complicated, but overall the relative ratios came out in the end, he says.

The study also selected only successful and productive CubeSat missions for its analysis. Caspi admits that more than half of CubeSat missions fail to launch and transmit usable data, and only about 25% produce data of the caliber of the missions represented in the study. Larger missions, on the other hand, are over 90% successful, Zesta says.

But for Spence, the fact that CubeSats still have room for improvement is part of what makes them exciting. “CubeSats are still a bit like the Wild West,” says Spence. “It’s a calculated risk, it’s moving fast. For me, it’s just a lot of fun.”

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